Audio Routing Help. S4 + Focusrite Scarlett 6i6 + MixControl

Hi All,

Due to the current crash/freeze issue that the MK1 Kontrol S4 is facing on the Macbook pro Late 2013 make, I've gone and picked up a Focusrite Scarlett 6i6.
Unboxed it, Downloaded the latest firmware, Downloaded MixControl..yada yada the whole shebang..
Now I've got troubles listening to my monitor/cue mix on my headphones. I've managed to get signals on the master output.
My channels are set to: Master Output L1, R2 & Monitor Output L3, R4. on the Traktor preferences tab.
My problem is, I'm unable to hear the cue/monitor on my headphones which are connected to the Audio interface.
I'm sure I haven't set the functionality of this beast on the Software i.e the MixControl correctly!
Need some help. What would I need to route where?
For some reason I can't upload an image on this thread, So anyone who has a Focusrite may be able to help better.
Leave a message here so I can try to share the image either PM or by email.
Really need a quick workaround!
Thanks a million!